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Jan. 9, 1951 1 R. APARlclo VARIABLE FILTER scREEN 6 Sheets-Sheet 6 Filed March 14,' 1947 Patented Jan. 9, v1951 UNITEDl STATES PATENT OFFICE 20 Claims.

This invention relates to yvariable lter screens for regulating the transmission of light and other types of radiant energy, also corpuscular rays. Such a device is useful as a light glare screen for vehicles and airplanes and has many other uses hereafter referred to.

Ordinary lter screens have a fixed filtering action so that the intensity and/or the character of the light or other transmission cannot be varied. Also, such type of lter screens must be removed bodily from the path of transmission when no filtering action is desired.

*"A lter screen designed to overcome the objections of xed filtery screens by providing a variable filtering action is described and claimed in my copending application, S. N; 641 972, filed January 18, 1946, now VPatent 2,474,712, granted June 28, 1949. Such device comprises opposing parallel rigid transparent members mounted for movement laterally to and from each other to receive a layer of varying thickness of a suitable gaseous or liquid filtering medium. The lter fluid is supplied from a deformable resere voir directly communicating with the margins of the transparent members... When the transparent members are in face to face contact the; screen is; clear. Compression of the` reservoir forces nlter fluid therefrom between the transparent members.L By regulating the amount of pressure any desired thickness of filter layer may be introduced between the members. To insureuniform distribution and thickness of the filter layer both during and subsequent to adjustment the reservoir extends completely around the. transparent members and lter medium is delivered from the reservoir simultaneously around the entire periphery of the members. Any desired degree of filtering action is thus obtained. Various types of colored gases and liquids may be employed for the filter medium depending upon the particular use to which the filter screen is to be put.

The present Vinvention involves a variable lfilter screen of the same general character of my aforesaid prior patent application and involves, improvements in construction and operation v thereof.

vOne object of the present` invention is to insuremaintenance of the transparent members of a variable filter screen `in parallel relation under all conditions of spacing so that the thickness of the filtering layer between them and the filtering action will be uniform throughout all areas of the screen.

Another object of the invention is to improve the construction of the filter medium reservoir of a variable filter screen.

A further object of the invention is to provide improved means for regulating the delivery of filter medium between the reservoir and the spacebetween the transparent membersl of la variable lter screen.

Still another object of the invention is to provide improved actuating means for moving to-` benefits of the invention will be understood from the various embodiments of my invention illustrated in the appended drawings and the detail description thereof to follow.

In the drawings: p

Fig. l is a rear elevation of a variable 'lter screen according to the invention; 2I is an enlarged fragmentary cross-sec-l tion of the upper portion of the iilter screen shown in Fig. 1;

3 is an enlarged fragmentary cross-section taken on the line 3-3 of Fig. 1;

Fig. 4 is an enlarged fragmentary longitudinal section taken on the line -fi of Fig. 1;`

Fig. 5 is an enlarged fragmentary cross-*section corresponding to Fig. 3 but taken on the line 5--5 of Fig. 1;

Fig. 6 is a fragmentary top plan view of the upper lefthandfportion of the screen shown in Fig. l, certain parts being broken away to show interior construction; l

Fig. 7 is a fragmentary horizontal section taken approximately on the line 'l-- of Fig. 1; Fig. 3 is a fragmentary perspective view of a second embodiment of filter screen according'to the invention;

Fig. 9 is a fragmentary perspective view showing modification of certain details of construction of the embodiment of Fig. 8;

Figs. 10 and 11 are fragmentary views of twofurther embodiments of the invention;

Fig. l2 is a fragmentary perspective view of still another embodiment of the invention;

Fig. 13 is a perspective view of certain of the parts shown in Fig. 12; and

Fig. 14 is a fragmentary perspective view of still another embodiment of the invention.v

The variable filter screen shown in Figs. 1 through 7 comprises two rigid transparent members 23 and 2| of glass, synthetic plastic or any 3 other suitable transparent material having low inherent filtering characteristics, and having sufficient strength and thickness as not to warp or break when subject to moderate fluid pressure. Surrounding the margins of members and 2| is a deformable, closed reservoir 22 of flexible, Huid-tight material. Such reservoir is preferably molded of rubber or suit-able synthetic plastic as a one-piece unit and, as will be understood from Figs. 2, 3 and 6, extends continuously around the transparent members as a border. Along the lower side of members 20 and 2| reservoir 22 is of enlarged cross-section to provide a reservoir chamber 23 of substantial capacity so that sufiicient lter medium may be stored therein to form :a layer of substantial thickness between the sheets when delivered thereto from the reservoir. The chamber portions 24 and 25 along the top and opposite sides of the lter screen, respectively, are of substantially smaller cross-section and capacity and are able to supply filter medium from the top and side margins journalled in stationary blocks 43 and 44 mounted in an auxiliary housing 45. Threaded member 42 f has a reduced shaft portion 45 projecting outof the screen as rapidly as it is supplied at the bottom since all portions of the reservoir are in continuous communication.

AS best shown in Fig. 2 the margins of transparent members 26 and 2| are beveled in an outward direction. The inner margins of the opposite side walls of reservoir 22 are bifurcated to provide outer and inner portions 23 and 27. Such bifurcated reservoir margins and the beveled margins of the transparent members are clamped in sealing engagement with each other and secured to frame member 28 by an inner clamping frame 29. Screw connecting elements 39 extend between frame member 23l and clamping member 29. It will be observed that clamping member 29 is beveled with the same inclination as the margin of member 2| so as to insure a reliable Huid-tight seal between the reservoir and the member, also that clamping member 29 is of less thickness than the transparent member so that the two transparent members may be V brought into face to face contact. On the exposed side/'of the second transparent -with the wall of chamber 23 is a rigid pressure bar 36 which extends substantially the full length of housing 35, as will be understood from Fig. 4. Movement of pressure bar 35 laterally yforces the wall of reservoir chamber 23 inwardly to build up pressure in the filter fluid (not shown) contained in the entire reservoir, whereby the filter uid is forced between transparent members 29 and 2| as they are caused to separate by the pressure of the iluid.

y Actuation of pressure bar 36 is effected through a deformable spring steel strip 37 which is anchored -at one end of housing 35 by means of a stationary anchoring clamp 38 fixed to the inner wardly beyond block 44', and secured thereto by a set screw 4'? or by any other'suitable means is an actuating knob 48. Rotation of the knob and threaded member 42 shifts member 39 longitudinally, resulting in bowing inwardly of spring member 3l against pressure bar 35. Itis desirable that the arrangement of parts 4be such that pressure bar 36 can be moved laterally substantially completely across housing 35 until thev opposite side walls of reservoir chamber 23 are brought almost together, it being understood that the greater the degree to which reservoir chamber 23 can be collapsed the greater the amount of filter fluid that can beforced between transparent members 20 and 2|, and consequently the greater the ltering actionof the screen. Actuating spring member 3l is `secured to pressure bar 36 only in the central area thereof so that it may be free to bow relative to the pressure bar for substantial portions of its length adjacent opposite ends. Connection between members 3l and 35 may be effected by means of clamping elements 49, shown in Fig. 5.

Spring means are provided for returning transparent members 2i) and 2| together from spaced relation when the pressure bar is retracted to permit fluid between sheets to return to the reservoir. Correctly speaking, upon the release of fluid pressure the spring means forces theliquid back into the reservoir. Such spring means include a series of spring metal clamps 59 arranged at recurrent intervals along the top vand sides ofthe screen as indicated in Fig. `1, such spring clamps embracing and being welded or otherwise securedto frame members 23 and 3|. As will be understood from Fig'. 2 members 55 are of suiiicient length to arch over reservoir 22 in such manner as not to constrict the reservoir. v

The spring means provided alongy the lower pansion springsv5| engageable with the movableV frame portion oftransp-arent member 2|. As

shown in Fig. 5 such springs are supported iny tubular housings 52 secured tothe top of housing 35. The outer portions of housings 572 are threaded to receive adjustment screws 53 by which the tension of springs 5i against the transparent member 2,! is adjusted. As willbe understood in Fig. l the adjustable springs, twoor more, are mounted in equal number on opposite sides of the mid point of the screen sov as'k to make itv easier to equalize thewtension along 'the bottom of transparent member 2| as well as equalizing the tension at the bottom with the tension provided by spring clamps 55, or compensate for accidental Variation between the tension of the individual spring clamps 5 9. Y

As shown in Fig. 3 top wall 54 of rigid housing 35 terminates in an inner edge 54 suiciently spaced from transparent member 2| and the parts associated with the lower margin thereof to provide clearance for lateral movement when lter medium forces transparent member 2| into spaced relation with member? 20. The gap providing such clearance maybe covered by a pro- I Wall 33 of reservoir 22.

cases .only .the enlarged chamber portion 2 3A of reservoir 22 extending along the. bottom of the .lter screenand clam-ping springs A50 are also encased byia 4aexible `channel-shaped. housing 55 of molded rubber or other similar material as shown in Figs. l,

2y .and 6. The side wall 5.6 of such. housing covers thaw-holeface of rigid frame member 2:8 andxis .cemented or otherwise secured. thereto.

lower end of sidewall 5|gis an inturned flange 5l .covering 'the lower ends of frame member 2.8 and At the side. wai-i 2.6. of .reservoir 2-2. A. resment bead 'nlv projects lateral-1y outwardlyI from the lower end y `pt .side wall 56 and extends completely around thefilter screen. By reason of the resilient chan-A .r acter of the side wall 55 and its covering: of all exposedmetal parts. on the forward side ofv trans'- parentmember 20 itzprovidesa suitable cushioning. vlayer adapting the. screen to. be disposed in face to facev contact with a windshield of a ve:- hicle, airplane front window or the like. Bead will form an eiective seal with the window.. The inner side wall 59 of housing 55 is. cemented or otherwiseseoured to movable frame meinbei: il and its .inner end has an inturned flange @covering the lower end ofA member 3| and side Thus. by the combination of rigid lower housing 3.5 and flexible housing 55 they-reservoir Q22 and .all other parts associated withthe margins of transparent members 29 and 'gt are. framed and encased..

To mount. the lter screen in windshields for windowsl of various sizes extensible supporting :means are .provided along the opposite side of the iter screen. As will .be understood from Figs. l and 'l rigid frame member 28 on the front side of transparent member 210.. is provided with a series .of projectingfwings which are covered by protective .extension 6| of side wall .56 of flexible housing 55. .Mounted on an upper pair of projecting wings of frame member 28: are rigid blocks 52 and 63 bored to loosely receive an elongated screw element. 164 having at its upper end a flat, thinedged foot 65 adapted to .be inserted between B window pane and itsy supporting frame. Rotat- .ablebetween blocks 62 and63: isa nut 6B threaded on vscrew element 64. Rotation of nut 6.6 causes the screw element to extend and retract. in a vertical direction, Similar screw element -E'l having a similar foot 68 is. mounted in the same manner adjacent the lower portion of the screen for vertical adjustment. Because of the extensibility of screw elements 64 and 61 the screen may be A adapted to be secured in windows of greater` height and area than the overall dimensionsA of the lter screen.

` It desired the :reservoir for the filter medium maybe of. substantial cross-section and comp-ressi'lole around the entire filter screen Vas illustrated bythe embodiment of Fig. .8. There the transparent members '|0 and 1| are surrounded 'by a collapsible .reservoir 12 of rubber vor other suitable material having margins sealed to the marsins of transparent members in the manner preidously explained. The reservoir is encased throughout its .circumference by a rigid metal trame-comprising an outer frame member 13 rigid with transitarent member 19 anda deep hollow tramov member T4 suitably secured to framemem- `.her 1.3. Instead of .employing ad'iustable spring means at one margin of the screen in association with spring .clamps at the othermargins, ad-

The'sides and top of the reservoir;

justable spring.y meansy arer in the, present embodiment employed at spaced intervals along all'mar.- gins. of the screen. kSuch means include coil springs 'l5 adjustable through screw 1.6 and supported in tubular housing fixed interiorly of frame 14. The springs act against the margin of movable transparentmember to urge the latter towards transparent member l0. The various springs are carefully adj-usted after the screen is ready for operation to insure parallelism between transparent members 'l0 and ll. The amount of tension applied on transparent. member 'll will be determined by the amount of pressure developed in the lter medium and the force Irequired to move transparent member 1| towards member "l0 when the fluid pressure is .released to return the fil-ter medium .to the reservoir from between the ytransparent members. 4

vTo collapse reservoir 12 a rigid frame-like pressure member 'I8 is movably mounted in frame 14 to act against reservoir '|2 throughout itsfcircumference. Rigid withY pressure member '|8 at the lower side ofthe screen is a strong metallic sleeve T9 slidable with a close fit in bore 89 of rotatable actuating knob 8|'. Outward-ly of bore 80 is a threaded bore 82` of reduced cross-section in which is threaded an actuating screw member 83 which extends through sleeve T9 and acts against pressure member '|8. Actuati-ng knob 8| is prol vided at. its inner end with a circumferential groove 84A engageable with themargin of an apertured supporting member 8.5 fixed to frame 14. Rotation of actuating knob 8| causes screw 83 to move the entire pressure member 18 laterally, tilting movement of the pressure member being prevented by reason of sleeve 19.

The inner edge 8B of frame member 14 is spaced suiiciently from transparent member 1| to permit lateral movement of the latter member away ber of the lter screen as shown in Fig. 9. There the transparent members and 9| are surrounded throughout their periphery by a reservoir 92 encased in a` rigid frame member 93. The side wall of frame member 93 is formed with a thickened portion 94 having at its inner side a socket 95 and seating spring 96 acting against transparent member 9|. Outwardly of socket 95 is a threaded bore 91 for adjustment screw 98 acting against spring 96 through disc 99. As in the embodiment of Fig. 8 the adiustable spring means just described will be provided at recurrent intervals around the entire circumference. of the screen. For some purposes it may be desirable to dispense with the individual tensioning springs for themovable transparent member and incorporate the function thereof inthe frame of the filter screen. This is illustrated in Fig. 10. There the transparent members |00 and [0I are surrounded by and sealed to the collapsible reservoir ||J2 as previously described. Encasing the reservoir is a rigid front metallic frame member |03 xed to transparent member |.00 and a hollow frame member |04 of resilient metal. The inner margin |05 of. the lower wall |06 of spring frame member |04 engages the parts associated with the margin of transparent member lill to-urge the latter member towards transpar-ent member |00. It is apparent, of course, that spring frame member ili must be precision stamped or otherwise formed to insure .parallelism under all ,conditions between transparent members Ii and lill. In Fig. 10, as in Fig. 9, the filter medium reservoir is intended to be collapsed throughout its periphery. The pressure member for collapsing lthe same has not been shown but it will be understood by reference to the foregoing description of Fig. 8. i v Fig. 11 illustrates a further. form of spring frame designed to tension transparent members towards each other where a portion of the filter medium reservoir is of small cross-section as in the embodiment of Figs. 1 to 7. Transparent members |||i and l l'along one or. more of their edges are sealed to a deformable reservoir portion |02' of relatively small cross-section and communicating with an enlarged collapsible reservoir portion extending along one or more of the further edges of the screen. Encasing reservoir portion lf2 and engaging with the parts associated with the margins of transparent members lli) and is a channel-shaped frame H3 of spring metal. The collapsible portion of the reservoir may be encased in a spring frame, as in the embodiment offFig. or may be supported in a rigid frame provided with a series of adjustable springs as in the embodiments of Figs. l to 'Z and Fig. 3.

In the various embodiments so far described the filter screens are adjusted by varying the pressure applied to the filter medium reservoir by suitable actuating means and providing spring means for urging the transparent members towards each other. It is also possibleto apply a continuous pressure to the iilter medium reservoir and to adjust the screen by regulating the spacing between the transparent members positively. Such an arrangement is illustrated in Fig. 12.- As in the embodiment'of Fig. 8 transparent members i2@ and l2| are surrounded on -all sides and sealed to a'collapsible reservoir |23. Encasing the reservoir and rigid with transparent member |23 is a rigid frame comprising members |213 and |25. Mounted in frame member |2a'i along'all edges of the screen are a series of pressure bars or plates |23 engageabl-evvith reservoir |23 and constantly tending to collapse the same through force applied thereto by relatively strong, expansion coil springs l2? which may or may not be provided with screw or other actuating means serving to regulate the positionV of 'movable transparent member |2| relative vto stationary transparent member |29. Various types of means which will serve such purpose and insure parallelism between the transparent members may be employed. The form of such means shown in Figs. 12 and 13 includes a rigid frame |28 rigid and movable with transparent member |2| provided with a series of horizontally inclined wedge surfaces' |29 and |3IJ.z1Coactive 'with memberV |28 Vis afcomplementary lmovable actuating frame |3| having wedge surfaces intertting with wedge surfaces |29 and |30. Actuating frame member |3| is supported for horizontal move-ment within frame member |25 in a fixed plane :by means of stationary guides within the frame at all sides thereof such as blocks |32 and |33. Horizontal movement of frame member |3| in sliding engagement with blocks |32 and |33 to the "f t forces frame member |28 and transparent me ber |2| towards transparent member |23. "Mov ment of frame member |3| to the righthand limit of the Wedge surfaces produces maximum spaciing between the transparent members. Such movement is effected by a reciprocating lever arm |34 having a ball and socket connection |35.; |36 with actuating frame member |3| and fulcrur'nir'ig in a resilient bushing |31 of rubber4 or othersuitable material secured -to hollow framel'lg. f When actuating frame member ...|3I is moved to the left by lever arm |34 the pressurepr duced on reservo-ir |23 by springsf|2l will f0.1"

lter iiuid between transparent members i2 il 14and |2|. Movement of actuating frame member-:|131 f to the right will force filter fluid from thelspabb between the transparent members back in ''o reservoir |23 against the pressure exerted on the rle'serevl voir bypressure members |21. This form of the invention requires no tensioning springs" .'lgajssblciation with transparent member |2|.sinc' 'e such members are maintained in parallelismfan'dione member is movable towards the other through coactng wedge frame members |23 and i315 1t may be said that the actuating means-'for developing fluid pressure and for adjusting the transparent members in the present form aret'n'e reverse of the actuaing means employed in thic previously described embodiments of the ini/elfi; tion. Here the transparent membersare adjusted through positive actuating means and Aspring means are employed to develop pressure gon the filter fluid. In the earlier forms of the invenftion the transparent mem-bers are adjusted spring means and positive means are employe'dtp develop pressure in the'filter medium. E n x The further embodiment of the invention shofwn in Fig. 14 employs the same operating principl'e'f the embodiment of Figs. 12 and 13-'in'` a circular form of iilter screen and with `some modificatidn in certain of the operating parts. The. circulai1 transparent members |40 and |4| of glass Vor other suitable rigid transparent material are surrounded by an annular collapsible reservoir l|412 forlter medium. One bifurcated margin of reservoir @|42 is secured in sealing engagementvvith thebeveled edge of transparent member M3 and 'to al'rig'id annular frame member |43 by a beveled clamping ring. The bifurcated opposite margin o-f reservoir m2 is secured in sealing engagement'A with Ithe bevel edge of transparent member Ml f and supporting frame member |65 4by a beveled clamping rirfg |46. Secured to front framev member is a hollow annular frame member |41 fencasm'g reservoir |42.

` Compression of reservoir |42 to force iilter'fl d between transparent members M3 and i-:iiiis effected by a strong elastic annular bandV his olf rubber or equivalent material. lSuch band may be endless or of adjustable length and is tightly stretched about the outer periphery of reservoir |612 to be capable of contracting the reservir sumciently to force filter iiuid between the trans"L parent members to the maximuml layerthickn'ess desired. v f i L j e '.As Yin the form of the invention 'shown-'in Figs.

9 l2 and `13 adjustment Aof the `spacing of transparent members |40 and 14| is `effected through positive actuating means. Such means include an actuating ring `|49 mounted for rotation interiorly of inner wall '|50 of hollow frame member |41. Secured to and vprojecting outwardly from ring |49 in a common circumferential plane vare three or more equally spaced control fingers or pins |5| which slidably engage annular frame member |45 of movable transparent member |4|. The opposite sides -of pins |5| engage inclined cam or wedge surfaces |52 formed around the inner periphery of inner wall |50 of hollow frame member |41. Rotation of actuating ring |49 in a clockwise direction causes pins |5| tojride along cam surfaces |52 in a manner to shift ring |49 laterally inward so that lframe |45 and transparent member -|4| are moved towards transparent Imember |40. Rotation of ring |49 in a counterclockwise direction permits `the ring to shift outwardly a distance equal to the maximum depth of cam surfaces |52.

The contractual force of elastic band |48 on reservoir |42 forces filter fluid from the reservoir between the transparent members, and forces the members apart 'and moves actuating ring 49 outwardly a distance determined by the position of pins |5| on cam surfaces |52. Rotation of ring |49 moves the ltransparent members together .and forces the filter fluid from the lspace between the .members back into reservoir '|42 ragainst vthe vcontractual forces of band |48.

The filter medium has 'been omitted from the drawings for purposes vof clarity but it will be understood that the same fills the reservoirs in all embodiments. The filter medium may ybe selected from a wide range of materials dependving upon the function 'to which the screen is to be put. Thus various colored gases maybe employed. Preferably, however, a colored liquid is used, of a type that will not absorb gas which might be evolved as gas bubbles when the screen is in use. In some vcases water is satisfactory, but to avoid adverse effects at low temperature it is better to use ethyl alcohol, glycol, glycerine, other alcohols, or benzol, or a mixture of one or more of these vand water. Hydrocarbon derivatives such as paraffin can also be employed as 'well as many other types of liquids. Dissolved or fine suspended coloring matter may be employed in the filter liquid. If the screen 'is to be-'used for filtering light selection of the coloring Amatter will vbe determined by whether it 'is desired to vary the intensity of transmission over all the spectrum, or to particularly control the transmission `of selected vportions of the spectrum. Blue or other aniline dyes will be found suitable for many purposes.

'It is also desirable to include on the filter medium va preservative or sterilizing agent which will prevent formation `of organic `or `other deposits in the reservoir land .on `the transparent members which .might :interfere with Vclarity of the filter medium. Phenol can be 4employed .for thisv .purpose.

`One :example of filter medium yparticularly sui-table .for glareshields. includes .a mixture of gwater, 125% A.ethyl alcohol, .50% ,glycerina r2 grains vphenol Aper liter and .aniline blue in amount to give a comparatively `.concentrated solution.

The ladjustable lter screen `of the invention fis capable-of Aadaptation 4for a variety of purposes as -aflight lter. It may be :removably mounted ,in association with windows of motor and railwyffvehicles, :airplanes and ships. It may also be v10 installed Apermanently as a substitute for .a window `in such various forms of transportation and in buildings. iIt .also may be employed singly or in a series containing ydifferent colored lter `mediums to produce colored lighting effects for .stage lighting and other'purposes. It is equally .useful for use in light measuring and other scientific optical apparatus and `for photographic purposes. Again, it may be employed, preferably in its circular forms, as a glare screen in conjunction with gun sights and airplane bomb sights.

rThe invention is not limited to the filtration of visible light but can be :employed `with appropriate absorbent or filtering media in conjunction with heatlng or infra-red and `ultrafviolet radiations beyond the visible light spec` trum, for -X-rays, gamma rays and cosmic rays'. Likewise, it canbeemployed `to determine the Aintensity of corpuscul-ar radiant energy o1' of ionizing particles such as alpha, beta, deuteronic and protonic particles and 'other types of particle of atomic structure. e It will be understood that the shape of my adjustable filter screen can vbe determined at will, that the forms of -supporting 4frames shown are .merely illustrative vand that the specific means for adjusting Athe spacing of the transparent members and for Vdeveloping pressure for forcing the filter fluid from the surrounding reservoir in-to the screen are capable of a wide range vof modification and equivalency. Accord Lingly, the yscope of the invention is to be Iadjudged in vaccordance with the appended claims.

I claim: k 1. A variable filter screen comprising la pair of rigid, opposing parallel transparent members laterally movable to and from each other, a'deformable closed -flexible thin-walled reservoir for filter fluid extending around the transparent members outwardly of the margins of the trans-i parent members and having laterally separable opposing margins in fluid-tight connection with Athe opposing margins of the transparent members, Aa hollow frame extending around the transparent members and encasing the reservoir, the outer surface of the thi-n wall of the reservoir being free `for flexing movement relative to the interior wall of the fra-me, and pressure means operative to compress at least a portion of the reservoir within the frame and adapted to force filter fluid .from all areas of the reservoir'between the transparent members.

2. A variable filter screen comprising a pair of rigid, opposing parallel transparent members laterally movable to `and from each other, a deformable closed flexible thin-walled reservoir for filter fluid extending around the transparent members outwardly of the .margins of the transf parent members and having .laterally separable margins 'in .fluid-'tight connection with the oppos` ing margins of the transparent members, a `hol-- low .frame vrigid with one ofthe transparent members extending around the transparent members and .encasing the reservoir., the vouter surface of the thin wall .of the reservoir being free for ,flexing movement relative to vthe .interior walljof -`the frame., and pressure means operative vto. compress the .reservoir in the frame `and adapted to force .filter .fluid from the reservoir between the transparent members.

3. A variable Yfilter screen comprising a pair of rigid, opposing parallel transparent members lateral-1y movable to :and .from .each other, a -de- 75 .formable .closed flexible thin-walled reservoir for margins in Huid-tight connection with the `opposing margins of the transparent members, a g

hollow frame extending around the transparent members and encasing the reservoir, said frame for at least a portion of its circumference having 'laterally separable opposing exible side walls ar- Tranged to move to and from each other with f lateral movement of the transparent members, and pressure means for compressingr the reser- `.Voir and adapted to force fluid between the transparent members.

- 4. A variable lter screen comprising a pair of -:rigid, opposing parallel transparent members laterally movable to and from'each other, a deformable flexible thin-walled reservoir for filter yfluid extending around the transparent members voutwardly of the margins of the transparent L vmembers and having laterally separable margins in fluid-tight connection with the opposing margins of the transparent members, a hollow met-al frame surrounding the transparent members and encasing the reservoir and in which thethin wall of the reservoir is capable of independent movement, and pressure means for compressing the reservoir within the frame and adapted to force yfilter fluid from the reservoir between the transparent members. l

-x 5. A variable ter screen comprising a pairv of rigid, Aopposing parallel transparent members laterally movable to and from each other, a deformable flexible thin-walled reservoir for filter fluid extending around the transparent mem- Y bers outwardly of the margins of the transparent members and having laterally separable margins'in fluid-tight connection with the opposing margins of the transparent members, a hollow spring metal frame surrounding transparent members, said frame encasing the reserto force lilter fluid from the reservoir betweenk the transparent members.

6. A variable lter screen comprising a pair 'of rigid, opposing parallel transparent members lat- Y erally movable to and from each other, a deformable flexible thin-walled reservoir for filter uid extending around the transparent members outwardly of the margins of the transparent members and having laterally separable margins in lfluid-tight connection with the opposing margins of the transparent members, said reservoir having an enlarged cross-section and capacity alongat least one side of the transparent members and being of smaller cross-section and capacity along the remaining sides of the transparent members, a rigid hollow frame portion secured to one or" the transparent members encasing the portion of the reservoir of enlarged cross-section, a flexible hollow frame portion encasing the portion of the reservoir of smaller cross-section, and pressure means for compressing the portion of the reservoir of enlarged crosssection within the rigid frame portion. '7. A variable filter screen comprising apair of rigid, opposing parallel transparent members laterally movable to and from each other', a deformable flexible thin-walled reservoir for filter fluid extending around the transparent members outwardly of the margins of the transparent members and having laterally separable margins in fluid-tight connection with the opposing margins of the transparent members, a-'rigid'supporting frame secured to one -of the transparent members, means supporting the other transparent member for lateral movement relative to the frame and to said rst transparent member, ex;- tensibe anchoring means movably mounted on the frame for projection outwardly beyond opposite side margins of the transparent members and adapted to engage a supporting frame of lar-ger area than'the transparent members, and pressure means for compressing thereservoir and adapted to force filter fluid from the reservoirk between the rtransparent members. p

8. A variable filter screen comprising a pair o rigid, opposing parallel transparent members laterally movable to and from each other; a de formable flexible thin-walled reservoir for filter fluid extending around the ytransparent members outwardly of the margins of the transparent members and having lateraly separable margins in fluid-tight connection with the opposing mar.- gins of the transparent members, a cushioning frame member of resilient material secured to the margins of one of the transparent members on the exposed face thereof adapted to rest against a nat surface, means supporting the other transparent member for lateral movement relative to the rst frame member and said cushioning frame, and pressure meansV adapted to force lter fluid from the reservoir between the transparent members. y .r y

9. A variable filter screen comprising a pair'of rigid, opposing parallel transparent vmembers laterally movable to and from each other, spring means located on opposite side margins of the transparent members urging said members towards each other, means for adjusting the relative tensionof spring means on said opposite side margins and adapted to secure parallelism of the transparent members, a closed reservoir adapted to contain a lter uid and having laterally separable opposing margins innuid-tight connection with opposing margins of the respective transparent members, and pressure means operative"A to force lter fluid from the reservoir between the transparent members against the opposition lof .the spring means. o 10. A variable filter screen comprising a pair of rigid, opposing parallel transparent members laterally movable to and from each other,

rigid with one of the transparent members, adj

justable spring means mounted on the frame and engageable with the second transparent member to yieldingly urge said members toward each other, a closed reservoir adapted to contain a 'lter iiuid and` having laterally separable opposing margins in fluid-tight connection with opposing margins of the respective transparent members, and pressure means operative to force filter fluid from the reservoir between the transparent members against the opposition of the spring means. ',f;

'11. A Vvariable filterscreen comprising a'paj'ir of rigid, opposing paral el `transparent members laterally movable to and from each other, a ser-ies of spring clamps embracing and en'gageable with opposing margins of the transparentmembers at recurrent points and yieldingly urging the transparent members towards each other, adjustable spring means engageable with the margin of one of the transparent members andyieldably urging the transparent members'towards each other; means for adjusting said latter springl means'so as to secure parallelism between the transparent members, a closed reservoir adapted to contain a liter fluidand having laterally separable 'opposing margins in uid-tight connection with' 13 opposing margins of the respective transparent members, and pressure means operative to force filter fluid from the reservoir between the transparent members against the opposition of the spring means.

12, A variable lter screen comprising a pair mirigid; opposing paral'el transparent members laterally movable to and from each other, a deformable closed flexible thin-walled reservoir for lter fluid extending around ythe transparent membersv outwardly of the margins of the transparent members having laterally separable opposing `margins in fluid-tight connection with pposing margins of the transparent members, a rigid hollow frame surrounding the transparent members and encasing the reservoir, means mounted Within the frame operative to compress the reservoir-.on all sides of the transparent members, and means for laterally moving the transparent members together from spaced relation. 135A variable lter screen comprising a pair of rigid, opposing parallel transparent members laterally movable to and from each other, a deformable dosed flexible thin-walled reservoir for lter fluid extending around the transparent members outwardly of the margins of the transparent members having laterally separable opposingA margins in fluid-tight connection with opposing margins of the transparent members, a

rigid hollow frame surrounding the transparent members and encasing the reservoir, resilient pressure means mounted within the frame operative to compress the reservoir and adapted to force fluid from the reservoir between the transparent members, and means operable to laterally move the transparent members together against the fluid pressure developed by the resilient pressure means.

14. A variable filter screen comprising a pair of rigid, opposing parallel transparent members laterally movable to and from each other, a deformable closed exible thinwalled reservor for lter fluid extending around the transparent members outwardly of the margins of the transparent members having laterally separable opposing margins in fluid-tight connection with opposing margins oi the transparent members, a rigid hollow frame surrounding the transparent members and encasing the reservoir, resilient pressure means mounted within the frame outward`y of the reservoir and operative to contract the reservoir circumferentially for forcing lter fluid from the reservoir between the transparent members, and means operable to laterally move the transparent members together against the fluid pressure developed by the resilient pressure means.

15. A variable lter screen comprising a Vpair of rigid, opposingparallel transparent members laterally movab'e to and from each other, a deformabe closed flexible thin-walled reservoir for lter fluid extending around `the transparent members outwardly of the margins or" the transparent members having laterally separable onposing margins in fluid-tight connection with opposing margins of the transparent members, a rigid hollow frame surrounding the transparent members and encasing the reservoir, resilient pressure means mounted within the frame operative to compress the reservoir and adapted to force filter fluid from the reservoir between the transparent members, and cam operated means mounted in the frame coactive with one of the transparent members to move the same laterally towards the other transparent member against me huid pressure developed by th resilient uuidl pressure means.

16. A` variable filter screen comprising a pair of rigid, opposing parallel transparent members laterally movable to and from each. other, a deformable closed flexible thin-walled reservoir for lter ilud extending around the transparent members outwardly of the margins of the translparent members having laterally separable op-i posing margins in fluid-tight connection with opposing margins of the transparent members, resilient pressure means constantly tending to compress the reservoir adapted to force lter uid from the reservoir between the transparent members and laterally move said members apart, and means coactive with the transparent members and operative to regulate their lateral position relative to leach other. 5

17. A variable 'filter screen comprising a pair of rigid, opposing parallel transparent members laterally movable vto and from each other, a de -I formable closed flexible thin-walled reservoir for ilter fluid extending around the transparent members outwardly of the margins of the transparent members having lateraly separable opposing margins in fluid-tight connection with opposing margins of the transparent members, resilient pressure means surrounding the reservoir constantly tending to contract the reservoir circumferentially adapted to force lter fluid from the reservoir between the transparent members and laterally move the transparent members apart and means operative to latfrally move the transparent members together and adapted to cause the lter fluid between the transparent members to ow into the reservoir and expand the reservoir against the pressure of the resilient pressure means.

18. A variable lter screen comprising a pair of rigid, opposing parallel transparent members of circular form, movable laterally to and from each other, an annular deformable closed flexible thin-walled reservoir adapted to contain filter ilud surrounding said circular transparent members outwardly of the margins of the transparent members and having laterally separable margins in fluid-tight connection with the opposing margins of the transparent members, an annular hollow frame secured around the margin of one of the transparent members and encasing the reservoir, means operative to compress the reservoir within the frame and adapted to force lter iluid between the transparent members, and means on the frame operable to laterally move the transparent members towards each other.

19. A Variable screen compr. sing a pair of rigid, opposing parallel transparent members of circular form, movable laterally to and from each other, an annular deformable closed flexible thinwalled reservoir adapted to contain lter fluid surrounding said circular transparent members outwardly of the margins of the transparent members and having laterally separable margins in duid-tight connection with the opposng margins of the transparent members, an annular hollow frame secured around the margin of one` of the transparent members and encasing the reservoir, resilient pressure means within the casing adapted to compress the reservoir and force filter fluid between the transparent members, a ring mounted for rotation on the frame member and coactive with the second transparent member and actuating means responsive to rotation of the ring to move said ring laterally and move the second 15 transparent m'ember relative to the rst transparent member.

20. An adjustable filter screen comprising a pair of rigid, opposing parallel transparent members laterally movable to and from each other, spring means adapted to move the transparent members together from spaced relation, a deformable closed reservoir for filter fluid extending around the transparent members and having laterally separable opposing margins, a rigid stationary frame, a clamping member clamping the margin of one of the transparent members and one of the margins of the reservoir in sealingr relation and securing them to the frame, a movable frame, a second Clamping member clamping the margin of the second transparent member in sealing relation and securing them to said movable frame, a housing encasng the reservoir portion along'one edge of the transparent members and secured to the stationary frame, pressure means supported by the housing operable t0 compress the reservoir portion in the housing and adapted to force filter fluid from all areas of the reservoir between the transparent members, and spring means. f

LUIS RODRIGUEZ APARICIO.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,780,773 Wearham Nov. 4, 1930 1,782,328 Wearham Nov.'18, 1930 1,870,284 Drake Aug. 9, 1932 2,220,851 Blodgett Nov. 5, 1940 2,338,497 Dimmick Jan. 4, 1944 2,369,741 Jones et al. Feb. 20, 1945 2,474,712 Aparicio June 28, 1949 FOREIGN PATENTS Number Country Date Australia of 1932 

